1
|
# is-data-descriptor [](https://www.npmjs.com/package/is-data-descriptor) [](https://npmjs.org/package/is-data-descriptor) [](https://npmjs.org/package/is-data-descriptor) [](https://travis-ci.org/jonschlinkert/is-data-descriptor)
|
2
|
|
3
|
> Returns true if a value has the characteristics of a valid JavaScript data descriptor.
|
4
|
|
5
|
Please consider following this project's author, [Jon Schlinkert](https://github.com/jonschlinkert), and consider starring the project to show your :heart: and support.
|
6
|
|
7
|
## Install
|
8
|
|
9
|
Install with [npm](https://www.npmjs.com/):
|
10
|
|
11
|
```sh
|
12
|
$ npm install --save is-data-descriptor
|
13
|
```
|
14
|
|
15
|
## Usage
|
16
|
|
17
|
```js
|
18
|
var isDataDesc = require('is-data-descriptor');
|
19
|
```
|
20
|
|
21
|
## Examples
|
22
|
|
23
|
`true` when the descriptor has valid properties with valid values.
|
24
|
|
25
|
```js
|
26
|
// `value` can be anything
|
27
|
isDataDesc({value: 'foo'})
|
28
|
isDataDesc({value: function() {}})
|
29
|
isDataDesc({value: true})
|
30
|
//=> true
|
31
|
```
|
32
|
|
33
|
`false` when not an object
|
34
|
|
35
|
```js
|
36
|
isDataDesc('a')
|
37
|
//=> false
|
38
|
isDataDesc(null)
|
39
|
//=> false
|
40
|
isDataDesc([])
|
41
|
//=> false
|
42
|
```
|
43
|
|
44
|
`false` when the object has invalid properties
|
45
|
|
46
|
```js
|
47
|
isDataDesc({value: 'foo', bar: 'baz'})
|
48
|
//=> false
|
49
|
isDataDesc({value: 'foo', bar: 'baz'})
|
50
|
//=> false
|
51
|
isDataDesc({value: 'foo', get: function(){}})
|
52
|
//=> false
|
53
|
isDataDesc({get: function(){}, value: 'foo'})
|
54
|
//=> false
|
55
|
```
|
56
|
|
57
|
`false` when a value is not the correct type
|
58
|
|
59
|
```js
|
60
|
isDataDesc({value: 'foo', enumerable: 'foo'})
|
61
|
//=> false
|
62
|
isDataDesc({value: 'foo', configurable: 'foo'})
|
63
|
//=> false
|
64
|
isDataDesc({value: 'foo', writable: 'foo'})
|
65
|
//=> false
|
66
|
```
|
67
|
|
68
|
## Valid properties
|
69
|
|
70
|
The only valid data descriptor properties are the following:
|
71
|
|
72
|
* `configurable` (required)
|
73
|
* `enumerable` (required)
|
74
|
* `value` (optional)
|
75
|
* `writable` (optional)
|
76
|
|
77
|
To be a valid data descriptor, either `value` or `writable` must be defined.
|
78
|
|
79
|
**Invalid properties**
|
80
|
|
81
|
A descriptor may have additional _invalid_ properties (an error will **not** be thrown).
|
82
|
|
83
|
```js
|
84
|
var foo = {};
|
85
|
|
86
|
Object.defineProperty(foo, 'bar', {
|
87
|
enumerable: true,
|
88
|
whatever: 'blah', // invalid, but doesn't cause an error
|
89
|
get: function() {
|
90
|
return 'baz';
|
91
|
}
|
92
|
});
|
93
|
|
94
|
console.log(foo.bar);
|
95
|
//=> 'baz'
|
96
|
```
|
97
|
|
98
|
## About
|
99
|
|
100
|
<details>
|
101
|
<summary><strong>Contributing</strong></summary>
|
102
|
|
103
|
Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
|
104
|
|
105
|
</details>
|
106
|
|
107
|
<details>
|
108
|
<summary><strong>Running Tests</strong></summary>
|
109
|
|
110
|
Running and reviewing unit tests is a great way to get familiarized with a library and its API. You can install dependencies and run tests with the following command:
|
111
|
|
112
|
```sh
|
113
|
$ npm install && npm test
|
114
|
```
|
115
|
|
116
|
</details>
|
117
|
|
118
|
<details>
|
119
|
<summary><strong>Building docs</strong></summary>
|
120
|
|
121
|
_(This project's readme.md is generated by [verb](https://github.com/verbose/verb-generate-readme), please don't edit the readme directly. Any changes to the readme must be made in the [.verb.md](.verb.md) readme template.)_
|
122
|
|
123
|
To generate the readme, run the following command:
|
124
|
|
125
|
```sh
|
126
|
$ npm install -g verbose/verb#dev verb-generate-readme && verb
|
127
|
```
|
128
|
|
129
|
</details>
|
130
|
|
131
|
### Related projects
|
132
|
|
133
|
You might also be interested in these projects:
|
134
|
|
135
|
* [is-accessor-descriptor](https://www.npmjs.com/package/is-accessor-descriptor): Returns true if a value has the characteristics of a valid JavaScript accessor descriptor. | [homepage](https://github.com/jonschlinkert/is-accessor-descriptor "Returns true if a value has the characteristics of a valid JavaScript accessor descriptor.")
|
136
|
* [is-data-descriptor](https://www.npmjs.com/package/is-data-descriptor): Returns true if a value has the characteristics of a valid JavaScript data descriptor. | [homepage](https://github.com/jonschlinkert/is-data-descriptor "Returns true if a value has the characteristics of a valid JavaScript data descriptor.")
|
137
|
* [is-descriptor](https://www.npmjs.com/package/is-descriptor): Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for… [more](https://github.com/jonschlinkert/is-descriptor) | [homepage](https://github.com/jonschlinkert/is-descriptor "Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for data descriptors and accessor descriptors.")
|
138
|
* [isobject](https://www.npmjs.com/package/isobject): Returns true if the value is an object and not an array or null. | [homepage](https://github.com/jonschlinkert/isobject "Returns true if the value is an object and not an array or null.")
|
139
|
|
140
|
### Contributors
|
141
|
|
142
|
| **Commits** | **Contributor** |
|
143
|
| --- | --- |
|
144
|
| 21 | [jonschlinkert](https://github.com/jonschlinkert) |
|
145
|
| 2 | [realityking](https://github.com/realityking) |
|
146
|
|
147
|
### Author
|
148
|
|
149
|
**Jon Schlinkert**
|
150
|
|
151
|
* [github/jonschlinkert](https://github.com/jonschlinkert)
|
152
|
* [twitter/jonschlinkert](https://twitter.com/jonschlinkert)
|
153
|
|
154
|
### License
|
155
|
|
156
|
Copyright © 2017, [Jon Schlinkert](https://github.com/jonschlinkert).
|
157
|
Released under the [MIT License](LICENSE).
|
158
|
|
159
|
***
|
160
|
|
161
|
_This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.6.0, on November 01, 2017._
|